Section 5. Advanced nuclear reactor and fuel cycle systemWhat is the potential use of thorium in the future energy production technology?
Abstract
Today's nuclear technology has principally been based on the use of fissile U-235 and Pu-239. While the natural thorium isotope Th-232 can finally be transformed to a fissile U-233 nucleus following a thermal neutron capture reaction, the existence of thorium in the nature and its potential use in the nuclear technology were not unfortunately into account with a sufficient importance. This was probably because of the geological availability of natural resources of thorium and uranium. Global distributions of thorium and uranium reserves clearly indicate that in general some developed countries such as the USA, Canada, Australia have considerable uranium reserves and contrarily only some developing countries such as Brazil, Turkey, India, Egypt have considerable thorium reserves as being totally about 70 % of the global reserve. All technical parameters obtained from the studies on thorium fuel cycle during the last 50 years indicate that thorium fuel cycle can be used in most of reactor types already operated. In addition, accelerated-driven hybrid systems promise to use the thorium based nuclear fuels. So, thorium will probably be a nuclear material much more valuable than uranium in the future. For this reason, all developing countries having thorium reserves should focus their technological attentions to the evaluation of their national thorium resources like in the case of India. In this paper a brief story on the studies of thorium and its potential use in the future energy production technology have been summarized.
References (12)
- D.J. Wilson
The use of thorium as an alternative nuclear fuel
(1992) - B.A. Tapp et al.
Energy and mineral resources systems
(1990) Journal of Uranium Institute
(1999)- G.R. Choppin et al.
Nuclear Chemistry : Theory and Applications
- V.M. Mourogov
Nuclear power development : Global challenges and strategies
IAEA Bulletin
(1997)
Cited by (66)
Synergistic extraction and separation of thorium from rare earths in chloride media using mixture of Cextrant 230 and Cyanex 923
2024, Journal of Rare EarthsIn order to lower the usage of expensive Cyanex 923 and increase the extraction capacity of the system of Cextrant 230, the synergistic extraction of thorium from chloride media by a mixture of Cextrant 230 and Cyanex 923 was investigated. The maximum synergistic enhancement coefficient (R) of 1.53 is obtained at 1:1 molar ratio of Cextrant 230/ Cyanex 923. The synergistic extracted species of Th4+ is determined as ThCl4·2Cextrant 230·Cyanex 923. The synergistic extraction of Th4+ is an entropy-driven exothermic process. The loading capacity of 0.60 mol/L mixed extractant for thorium is about 17.10 g/L (calculated as ThO2), and the loaded thorium in the organic phase can be effectively stripped by distilled water. For comparison, rare earth cations are barely extracted under the similar conditions, suggesting that the mixtures can be applied to separate thorium from rare earths. A cascade extraction process was developed based on the synergistic extraction system to separate thorium from the hydrochloric acid leaching of bastnaesite. The content of thorium in the leaching solution decreases obviously from 19.90 mg/L to 1.4 μg/L by 3 stages of extraction, which is superior to sole Cextrant 230 or Cyanex 923. The introduction of Cextrant 230 into the extraction system not only lowers the usage of Cyanex 923 but also enhances the selective extraction of thorium at low acidity, implying that the synergistic extraction system can selectively extract thorium more efficiently and economically than the sole systems.
Stripping and recovery of U and Th from EHEHPA in rare earth separation plant
2024, Separation and Purification TechnologyA circular process comprising of striping, acidification, precipitation and separation was proposed for stripping and recovery of U and Th from 2-ethylhexyl phosphoric acid mono-2-ethylexyl ester (EHEHPA) in rare earth separation plant. In this process, U and Th could be stripped by sodium carbonate in one step, and the stripping efficiencies reach to 98.04% and 97.50%, respectively. After stripping, the organic phase, which split into heavy and light phase, can be merged into one organic phase after acidified and regenerated by 3 mol/L H2SO4. The extraction ability test and FT-IR results show that the regeneration organic phase renews to the level of new EHEHPA. Finally, 98.8% of U and 99.3% of Th were precipitated and recovered from the stripped liquor after adjust the pH to 13 by NaOH. The pregnant liquor can be repeated used in the stripping process after adding the concentration of carbonate (CO32−) to 1.2 mol/L. This novel approach is both environmentally friendly and economically feasible. It has significantly contribution to the recovery of U and Th in rare earth separation processing.
Thorium speciation in ilmenite concentrates from the Mandena deposit, Madagascar: Implications for environmental remediation and thorium beneficiation
2024, Applied GeochemistryPlacer ilmenite deposits are important sources for titanium dioxide production but are often radioactive due to elevated thorium and uranium contents, posing significant challenges to their upgrading and downstream commercial applications. In this contribution, we have investigated ilmenite concentrates containing 133 ppm Th and 12.8 ppm U from the Mandena deposit, Madagascar, using a wide range of analytical techniques: powder X-ray diffraction, electron microprobe analysis, quantitative evaluation of materials by scanning electron microscopy, inductively coupled plasma mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, synchrotron X-ray absorption spectroscopy, microbeam synchrotron X-ray fluorescence mapping, and microbeam synchrotron Laue X-ray diffraction analysis. Our data show that monazite-(Ce), mainly as discrete grains, accounts for ∼55% of Th in the Mandena ilmenite concentrates. Thorianite hosting the remaining Th at ∼45% is revealed by synchrotron Th LIII edge X-ray absorption near-edge structure and extended X-ray absorption fine structure analyses and is correlated with the degree of ilmenite alteration. These results suggest that thorianite probably formed from the alteration of ilmenite and precipitated on the surface of altered ilmenite. The presence of monazite-(Ce) and thorianite in the Mandena ilmenite concentrates is further supported by principal component analysis of trace elements. Our results suggest that combined magnetic separation and acid leaching are effective for reducing the Th (and U) abundances in the Mandena ilmenite concentrates, via the removal of Th-bearing minerals. These findings have important implications for both Th remediation and beneficiation. Moreover, the precipitation of thorianite on the surface of altered ilmenite is an effective method for attenuating the common radionuclide Th in surficial environments.
Uranium(VI) and thorium(IV) extraction by malonamides: Impact of ligand molecular topology on selectivity
2022, Journal of Molecular LiquidsUranium(VI) and thorium(IV) extraction from nitrate media with N,N′-dimethyl,N,N′-dibutylteradecylmalonamide (DMDBTDMA) and N,N,N′,N′-tetrahexylmalonamide (THMA) in toluene has been investigated. These two diamides are structural isomers, differing only in the position of alkyl chain substituents. With both ligands, the extraction of uranium(VI) and thorium(IV) is more efficient at higher acidity while uranium(VI)/thorium(IV) selectivity is higher at lower acidity, particularly with DMDBTDMA, for which an almost selective extraction of uranium(VI) has been observed. The selectivity difference between the two ligands has been proven to be mainly due to thorium(IV) extraction, which is strongly dependent on the malonamide molecular structure. On the other hand, uranium(VI) extraction follows the same trend with both DMDBTDMA and THMA. In-depth analysis of molecular and supramolecular features of extracting organic solutions suggests that the disparity of thorium(IV) extraction trends between the two malonamides can be linked to the difference in thorium(IV)-ligand interactions: thorium(IV) extraction appears to lead to rather stable classical coordination complexes with THMA, and more complex supramolecular species with DMDBTDMA. Altogether, these results suggest the prevalence of hydrophobic driven interactions for extraction of metallic cations with DMDBTDMA and electrostatic driven interactions in the case of THMA.
The efficient separation of thorium from rare earth using oxamic acid in hydrochloric acid medium
2020, Separation and Purification TechnologyThorium (Th) is a promising element that can be converted to fissile uranium for nuclear energy. A large amount of slag containing Th need to be effectively treated and stacked in rare earth (RE) industry. It is of importance to develop some novel processes for separating Th from REs using solvent extraction. The amide group was considered to have good selectivity for Th separation from REs. In order to solve the problem of RE entrainment during Th separation together with primary amine (N1923, (CnH2n+1)2CHNH2 n = 9–11) does not extract Th in hydrochloric acid system, three oxamic acid type extractants have been designed and synthesized in this paper. Among the extractants, the separation performance of 2-(dibenzylamino)-2-oxoacetic acid (DBOA) was indicated to be the best. As for the effective separation, the electron affinity of Th was larger, it was more preferred to coordinate with the extractant. The hydrogen ions released by the extractant could inhibit the extraction of REs rather than Th. Accordingly, Th could be separated from REs. Saponification process of oxamic acid extractant could be omitted in this separation process. By extracting Th using a lower concentration of oxamic acid selectively, not only the loss of RE could be reduced, but also a higher purity of Th could be obtained. Using a simplified fractional extraction experiment, the purity of RE in aqueous phase was increased to be 99.92% or higher, and the purity of obtained Th after stripping from loaded organic phase was increased to be 99.5%.
Basic design analysis of a heavy water-cooled thorium breeder reactor
2020, Nuclear Engineering and DesignCore design evaluation of heavy water cooled thorium breeding reactor has been investigated based on optimum basic design criteria such as fuel breeding capability and negative void reactivity coefficient value by adopting triangular fuel lattice and hexagonal core arrangement. Core burnup calculation and some thermal hydraulic parameters have been analyzed to evaluate the reactor core performances and to confirm the feasible design region based on the optimum results. Core burnup evaluation has confirmed the feasibility of heavy water-cooled thorium breeder reactor with negative void reactivity. Three batches refueling scheme is employed for 23-month refueling period. This system shows the breeding condition at the end of cycle for average core burnup of 38 GWd/t and it always gives negative void reactivity coefficient during reactor operation. In relation to thermal hydraulic analysis, the system achieves the maximum linear heat rate of 18.2 kW/m, maximum fuel temperature of 1066 °C and friction pressure drop of 0.046 MPa. The reactor has large margins due to the limitation of thermal hydraulic design point of view and some comparable result with the conventional reactor based on the obtained thermal hydraulic properties.